1. Field of the Invention
The present invention relates to an exchange-coupled film including ferromagnetic layers and an antiferromagnetic layer, a spin valve film using it, a thin film magnetic head, a magnetic head apparatus, and a magnetic recording/reproducing apparatus.
2. Related Background Art
The known thin film magnetic heads include thin film magnetic heads provided with a spin valve film in which an antiferromagnetic layer, a ferromagnetic layer, a nonmagnetic, conductive layer, and a ferromagnetic layer are successively stacked (e.g., Japanese examined Patent Publication No. 08-21166 and Japanese Patent Application Laid-Open No. 06-236527). In such thin film magnetic heads a direction of magnetization of the ferromagnetic layer in contact with the antiferromagnetic layer is pinned by exchange coupling between the antiferromagnetic layer and the ferromagnetic layer. In order to improve the reliability of the thin film magnetic heads, exchange coupling energy of the exchange-coupled film including the antiferromagnetic layer and the ferromagnetic layer exchange coupled with the antiferromagnetic layer needs to be sufficiently high.
The known exchange-coupled films include the exchange-coupled films using a PtMn layer and a CoFe layer (e.g., Japanese Patent Application Laid-Open No. 09-147325), the exchange-coupled films using an NiMn layer and a CoFe layer (e.g., Japanese Patent Applications Laid-Open No. 09-63021 and No. 09-50611), the exchange-coupled films using an IrMn layer and a CoFe layer (e.g., Japanese Patent Application Laid-Open No. 09-148132), the exchange-coupled films using an RuRhMn layer and an NiFe layer (e.g., Japanese Patent Application Laid-Open No. 10-242544), and so on.
There are other known exchange-coupled films in which the ferromagnetic layer thereof is comprised of a ferromagnetic layer sandwich of trilayered structure consisting of a ferromagnetic layer/a nonmagnetic metal intermediate layer/a ferromagnetic layer, so as to antiferromagnetically exchange couple the two ferromagnetic layers with each other, thereby achieving an effective increase of exchange coupling force from the antiferromagnetic layer to the ferromagnetic layer sandwich (e.g., Japanese Patent Application Laid-Open No. 2000-137906).
Furthermore, disclosed is a method of interposing a matching ferromagnetic layer between the antiferromagnetic layer and the ferromagnetic layer in the exchange-coupled film to enhance exchange coupling (e.g., Japanese Patent Application Laid-Open No. 09-82524).